Frequency dividing system for electric alternating currents



Oct. 19, 1943. H. LAUER 2,331,986

FREQUENCY DIVIDING SYSTEM FOR ELECTRIC ALTERNATING CURREN'IS Filed June 3, 1942 2 Sheets-Sheet 1 INVENTOR 63 64 HENR/ LAUER 9 HIS ATTORNEY.

2 Sheets-Sheet 2 H. LAUER Filed June 3, 1942 FREQUENCY DIVIDING SYSTEM FOR ELECTRIC ALTERNATING CURRENTS Oct. 19, 1943.

IN VE N TOR @i T? mi +5 components. said patent application for eliminating or-re- Patented Oct. 19, 1943 UNITED STATES PATENT m FREQUENCY DIVIDING SYSTEM FOR ELECTRIC ALTERNATING CURRENTS Henri Lauer, New York, N. Y. Application Jlln8r3, 1942, Serial raaezz 12"Claims. (01.250546) The present invention relates to a frequency dividing system for electric alternating currents permitting to obtain, from a single phase: alternating input voltage, an alternating output: voltage of sub-multiple frequency.

This frequency dividing system utilizes the properties of such frequency reducing devicesas are described in my- United States patent application, Serial Number 369,725 of December 712, i940, Patent No. 2,305,625, dated Dec. 22,. 19.42, or of certain other frequency reducing devices of odd or of even frequency transformation ratio. Without therefore limiting the present system to the use of the device disclosed: inmy said patent application, this system is, however, described in relation therewith, for the convenience of explanation. For greater simplicity of language, this device, as well as other devices which maybe used in its placeto perform a similar function, is designated here as a frequency divider;

' Referring to my aforesaid patent application, when an alternately reversed voltage .is applied to the input terminals of the device disclosed therein, a voltage is developed at the output terminals of said device, which reverses alternately at a sub-multiple frequency. If therefore, the applied input voltage reverses once duringevery cycle, as is the case, in particular, when thi's input voltage is of sinusoidal wave shape, the output voltage has a fundamental frequency which is a sub-multiple of that said input'voltage. But if the input alternating voltage isof nonsinusoidal wave shape and, say, has a polarity which reverses several times during every cycle of its fundamental frequency component, the frequency components of the output voltage of the device-may or may not be in the same frequency relations to each other as those of the input voltage, depending in particular on thefrequency transformation ratio of the device and onithe frequency composition of the input voltage. .In other words, the-simultaneous.frequencydivision, in a same ratio, of several frequency components of the input voltage is achieved by means ofthis device for only certain particular frequency, am: plitude and phaserelationsof the input voltage And the system described .in my ducing certain harmonics developed by the operation of the device and notpresent in the-original input voltage does not lift this limitation-70f the field of application of said device.

The object of the system forming the present invention is to permit the frequency division-pf not only a sinusoidal. alternating input voltage,

but also the frequencydivision, in asamel'ratio, of two simultaneously applied alternating input voltagesof different frequenciesand, impatienlar, of equal or approximately equal amplitudes, irrespective of the relatlve 'values of said,;f 1=e quencies, and in certain casesof-morethan two simultaneously applied; alternating input-voltages of different frequencies and; of, suitable {relative phases and amplitudes, g V I I a In this -system, ;the alternatinginput voltage, the component frequencies of. which. are to be divided, is not applied directly to the inputterminals ofv the frequeneydividen, but. is -,made,lto modulate an alternating icarrier currentgor voltageof higherfrequency. 'lhe invention then consists, after separating'the-frequency components of the thus modulated current .or voltage into upper or lower side frequency component bands'and suppressingthe carrierfrequency'. com.-

; ponent, in. applying the compcnentslofitheriipper side frequency band to the inputterminalslof afrequency divider as defined above and the components of the lower side frequency bandlto the input terminalsof another frequencydivi'der :of equal input-outputfrequency transformation ratio, demodulatingthe .output voltages @of. both of these two, dividers with a substantially sinusoidal alternating voltage havingai frequency which is a suh-rnultiple of, the frequencylo'fithe :said carrier current-in, the same ratio-asfthe frequency transformation ratio of the. two, dividers, and applying the .thus demodulated volt.- ages of the twondividersuponacommon circuit, in which the. low frequency-component currents or. voltages constitute theoutput currents, or volt,- ages-ofthe frequency-dividing system, means being furthermoreprovided,to give, such, suitable phase? relations to said currents or v.oltages;. as 'may be required, r

When "two frequency. dividers of equallratios are thus differently actuatem and, their output voltages demodulated, as described, .I havefound that, save in certain, particular instances the respective resulting-demodulated voltages he two dividers ,difier frorn each otherl in thei re spective frequency composition, or in. the relative amplitudes of. their various, frequency-com- ;ponents and that thealgebraidsum of these volt.- ages, as, obtained; when they are-applied to -a common circuit, constitutes a voltage'Whichds-a 120. 16 Complete and-closer sub-multiple frequency reproduction of the input voltage, thamtha-demodulated 'output voltage; of, either-divider taken individually, a s g g ,The nvention il e be ie ilmd fiq d39m the following description, when considered in relation to the accompanying drawings, in which Figure 1 is a wiring diagram of a frequency halving system according to the present invention, that is to say a frequency dividing system having an input-output frequency ratio of two to one. For simplicity, triode relays are shown in the drawing, but other suitable types of relays may be used in place of these; the filament heating circuits of allelectron tubes are omitted, for greater clearness of the drawing; and certain of the tube circuits may be altered to use common energizing and common biasing batteries or voltage sources, as is frequently done in practice.

Figure 2 is a schematic wiring diagram of the system, illustrating a different arrangement of the demodulating circuits,

Figure 3 is a schematic wiring diagram of the 7 system, illustrating a different arrangement of the sources of the carrier frequency alternating voltage and of the sub-multiple frequency sinusoidal alternating voltage.

Figure 4 is a wiring diagram of one of the circuit systems of a frequency divider similar to one of those used in the arrangement of Figure 1, but incorporating an additional amplification stage, as explained further below.

The system'illustrated in Figure 1 comprises a generator of substantially sinusoidal alternating voltage, the circuits of which are enclosed in the dot-and-dash line frame C; a frequency multiplier, enclosed within the frame E; a modulator, shown within the frame F; two filter circuits passing respectively the upper and lower side frequency band components of the modulated voltage and shown respectively within the frames G, H; two frequency dividers D and D of same input-output frequency ratio as the output-input frequency ratio of the frequency multiplier E; and demodulating, phase-adjusting, and output circuits shown in the lower part of the drawing. These various components of the frequency dividing system are briefly described below, before describing the operation of the system.

The circuits enclosed in the frame C represent a generator of alternating voltage of substantially sinusoidal wave shape. In the particular instance illustrated here, this is a usual form of triode oscillator, the triode having its grid and plate electrodes respectively connected to the ends of an inductance l6 and its filament connected to a suitable intermediate point of said inductance. The plate and grid of the triode I5 being given suitabl positive and-negative potentials, respectively, by means of the batteries l1, l8, and the inductance 16 being shunted by a condenser I9, continuous oscillations are sustained in the circult formed by the inductance l6 and condenser IS, the frequency of which is a function of the dimensions of said inductance and condenser.

Coupled to the inductance I6 is a coil 20, through which the oscillations generated in the circuit 16-49 energize a frequency multiplier, which is a frequency doubler in the present instance, constituted by the circuits enclosed in the frame E. This comprises two diodes 35, 36 having their filaments connected to each other, and their plate electrodes connected respectively to the ends of the coupling coil 20. A connection is also provided between the filaments and the middle point of the coil 20, which connection includes the primary winding of a transformer 31. As known, under the action of th alternating voltage induced in the coil 20 by the oscillating current flowing in the circuit [6-49, a

III

pulsating current of doubl frequency flows in the circuit branch comprising said primary winding of the transformer 31. The alternating voltage induced in the secondary winding of this transformer 31, which thus has a frequency equal to twice the frequency of the alternating current produced by the generator C, constitutes the carrier voltage mentioned in the earlier paragraphs of this specification.

This carrier voltage is impressed upon a modulator, the circuits of which are shown within the frame F. This is a conventional balanced modulator, which comprises two parallel-connected triodes38, 39, the plate circuits of which are energized by the battery 40, and the grids of which are given a suitable biasing potential by the battery 4|. The secondary winding of the transformer 31 is connected in the common branch of the grid circuits of the triodes 38, 39, so that the carrier voltage generated in this secondary winding through the operation of the frequency doubler E produces simultaneous and in-phase variations of the grid potentials of said triodes 38, 39. The grid circuits of these triodes also comprise the secondary winding of a transformer 42,

shunted by the usual high frequency by-pass condensers 43, 44, and so connected that an alternating current flowing in the primary winding of said transformer 42 produces opppositely directed alternating voltage variations of the grids of said triodes, which modulate in opposite directions the alternating plate current components of these tubes developed under the action of the carrier voltage. The terminals 45, 46 of the primary winding of the transformer 42 constitute the input terminals of the frequency dividing system, and it is the object of the operation of said system, as described further below, to produce an alternating voltage across its output terminals 61, 68, the largest components of which have frequencies which are respectively sub-multiples (in the present instance one-half) of those of the components of the alternating Xoltage impressed upon said input terminals 45,

Connected to the secondary terminals #1, 48 of the differential output transformer 49 of the modulator F are two filter circuits G, H, schematically represented as composed of condensers and inductance coils so disposed and connected that the filters G, H, pass respectively the upper and lower side frequency band components of the output voltage of the modulator F, that is to say those frequency components of said output voltage which have respectively greater and smaller frequencies than the carrier voltage produced by the multiplier E. Any other suitable arrangement may of course be used in place of those shown as G, H, for performing the same function. Through these filter circuits G, H, and through transformers 50, 5!, the actuating terminals 3|, 32 and I I, 12 of two frequency dividers D, D are connected respectively to the output terminals 41, 48 of the modulator F. The divider D is thus actuated by the upper side frequency band voltage components of the modulated output of the modulator F, while the divider D is actuated by the lower side frequency band voltage components of said modulator output.

The two frequency dividers D, D shown in the drawing are frequency halving devices, that is to say, they have an input-output frequency transformation ratio of two to one which corresponds to the two to one frequency transformation ratio of the frequency multiplier E. These frequency dividers are {similar toeachother, and respectively similar to the frequency halving-device illustrated inFigure-l o'fthe drawing appending to the specification of my aforesaid United'States Patent application, in which they are described in detail." I P r "I -he frequency dividerD, the various circuit elements of which are designated by the same numerals from I to l2 and letters Aand B as said'patent application, includes two circuit systerns A and B each of which comprises a revers ible apparatuscomposed of two triodes; I, -2 the plate circuits of which are energized, respectively-by a battery 3 in series with a resistance '5, and a battery 4- in series with resistance '8. The cathodes of the two tubes are connected to each other -by'resistances 6;? in series, and the grid electrode of each tube is connected to some suitable point o'f'the plate circuitpftheother. Each of the systems A, B also comprise two triodes 9, Ill having their filaments connected together, while their plates are respectively coniiec'ted to'the cathodes of tubes I andZ. The grids of tubes 9 and I of-system'A are connected respectively to suitable points of the plate-hir of tubes I and 2' of system B, while the grids of tubes '9 and 10 of system B are respectively connected to suitable points of the plate circuits of tubes 2 and l of system A, Finally, theinput terminals ll, l2 which receive the emanating voltage actuating the divider'are connected as followsrterminal I l is'connected to the filaments of tubes 9, to of system-B and to thecommon point of resistances -6, 1 of system -A, while terminal 12 is connected to the filaments of tubes :9, 10 of system A and to the common point of resistances 6, I of system B. v

A similar description applies to the frequency divider D, the various respective circuit elex" n:ents of which are designated in corresponding manner-by numerals from 2| to 32 and letters and-B; Output connections of the frequency tiivide'r D are made, through the wires, 13, I4, to the plate electrodes of the tubes 9 ID of its syste'm'B', while output connections of the frequency divider D are made, through'the wires 33, 34, to the plates of the tubes 29, 30 of its system B.

By means of these connections "I3, lithe-output voltage of "the frequency divider D is applied between the grid and "filanientof a coupling triode' 52, the plate circuit of which is energized by abatt'ery 53 and comprises the primary winding era transformer 54, The'secondary winding of thistransformer54 is included in a circuit 'compr ng an alternating current rectifier 55. On the other hand, the circuit of-thi rectifier *55;is coupled, through the transformer 56, to-the plate circuit ofa triode 51 energized by the battery 53, the grid circuit of which is actuated by a s 'bstantially sinusoidal voltage produced bythe generator C. For this purpose, the grid and filarnent of'the tube are "connected respectively tone grid and filament of the triod l5; s

Similarly, by means of "the connections 33-,'-3-'4,

voltage of the frequency divider is applied'betweenfthe grid and filament of a coupling ttiode"58, the plate circuit cfwhich is ener- ".2 d b 'th bat er 5 a e 't e Priy winding of'atrans'fformer 59. The secondary winding of this transformer 59 is included in However, for purposesiexplained laten-thejcom nection of the'tran'sformer fil'to the plate circuit of the triode 62 is made by way of aiphase adiusts ing device composed, in the example illustrated here, of a transformer 69 and theresistance 10. The primary windingzof this transformer 69 and the resistance-l0 are connected in seriesin the platecircuit of'the tube -62, whileoneendiof the secondary winding of the transformer .69 is connected to -a common point of the resistance '10 and the primary winding of said transformer -69. The other encl of the secondarywinding of this transformer 69 -and 'some suitable point of the resistance 10 are connected respectively to the-ends of theprimaryxwinding of the trans.-

respectiiiely -to the grid rand-filament. of thextrie forn ierflil. In this-manner, the alternating .cur-

rent component developed in the plate .circuitcof the triode 62 unden the-action of the. alternating grid voltage supplied toithis triode (by .the generator C, inducesin the circuit of thewrectifier 60,-an alternatingvoltage the phase orwhich may be adjusted by suitably choosing thereon:-

nection point of the primary winding QfithB transformer BI 'tO-the resistance J0, and adjusting the coupling of the two windings of" the transformer 69, which' windings 'may for this purpose be-made to be movable with respectcto each other. i

Finally, the circuitsof therectifiers .55sand 6fl quiescent operating condition. "The only voltage operatingin the' circuits of the re'ctifiers 5.5, .61! is then the alternating voltageof constant maximum "amplitude derived, through the tubes 151 and'BZ respectively;from the oscillator tube 1.5.

The currents operating in these rectifier circuits hence comprise high :frequencyacomponents, which areby-passedthrough the condensers 6,5, =66, and continuous components of constant-intensity, which, in flowing through the primary windings of the transformers 6,4,, induce no voltage inthe output circuit 6], 65.

It now an alternating voltage of sinusoidal -wave shapeis applied to the terminals 45, 4,6, the

operation of the balanced modulator F deiielpps,

composed, as known, of two sideefrequency components, the frequencies of which are respectively equal to the sum and difference ,of-the carrier frequency and ofthe frequency of the alternating voltage applied to the terminals .5; 45. These two side frequencyvoltagesbeing separatedby the filter circuits G, H, the lower frequency output'voltage component of the modulator F actuates, through the transformer 51, the terminals l1, l2 of the frequency divider'D, while the higher frequency output voltage componentof the modulator F actuates,through the transformer 50, the terminals 3!, 32of the frequency divider D.

These frequency dividers D, D! then produce alternating voltages across their respective terminals l3, I4 and-t3, 34 which have a much distorted 'wave shape,but thefundamental. frequencies of'which are respectively equal to onehalf the frequencies of the voltages applied to the terminals II, I2 and 3|, 32.,

The voltage thus developed across the terminals I3, I4 is impressed, through the coupling tube 52, and the transformer 54, upon the circuit of the alternating current rectifier 55. Upon this same rectifier circuit is applied the substan tially sinusoidal alternating voltage of one-half carrier frequency, supplied by the generator tube l5 through the coupling tube 51 and transformer 56. Alternating currents are then produced in the circuit of the rectifier 55, having frequencies respectively equal to those of the alternating voltages applied to said circuit, and to multiples of these frequencies, and the sums and differences of these frequencies. While the currents of higher frequencies are by-passed through the condenser 65, those of lower frequencies flow through the primary winding of the transformer 53, and induce in the secondary winding of the latter an alternating voltage having a wave shape which depends to some extent, in particular, on the characteristic of the rectifier 55, and a frequency equal to one-half the frequency of the voltage applied to the input terminals 45, 46 of the system.

Similarly, the voltage developed across the terminals 33, 34 of the frequency divider D is impressed, through the coupling tube 58 and transformer 59, upon the circuit of the alternating current rectifier 50. This same rectifier circuit receives a substantially sinusoidal alternating voltage of one-half carrier frequency from the generator tube I5, through the coupling tube 52 and transformer 6|. Here again, a voltage is produced in the secondary winding of the transformer 64, having a frequency equal to one-half the frequency of the voltage applied to the input terminals 45, 45 of the system.

The secondary windings of the transformers 63, 64 being connected in a common circuit, an alternating voltage is then obtained between the terminals 61, 68 of the latter, having a frequency equal to one-half the frequency of the alternating voltage applied to the input terminals 45, 46 and having a wave shape which approaches the sinusoidal wave shape of said applied input voltage, more closely, generally, than the voltages developed in either one of the transformers 63, 64.

This result is obtained, however, when the voltages developed by the two transformers 63, 64 are applied to the common output circuit 6|68 in proper mutual phase relation. Such a phase relation may be obtained by means of the phase adjusting device 59-10, which, in permitting to shift the phase of the voltage derived from the generator C in one of the two rectifier circuits correspondingly shifts the phase of the low frequency voltage developed in this same rectifier circuit, with respect to that developed in the other rectifier circuit. Such a phase shifting arrangement may be placed either between the circuit of the rectifier 60 and the generator C, as shown in the figure, or in similar manner between the circuit of the rectifier 55 and the generator C. Or else, it may be connected as a part of the coupling circuit between the modulator output terminals 41, 48 and the actuating terminals ll, l2 or I3, 32 of either one of the frequency dividers D, D, or as part of the coupling circuit between the output terminals I3, I4 or 33, 34 of one of said dividers D, D and the circuit of the corresponding rectifier 55 or '60.

0r again, it may be inserted between the output circuit 61-68 and the circuit of either one of the rectifiers 55 or 60.

Supposing now that, instead of being of sinusoidal wave shape, the alternating voltage applied to the input terminals 45, 46 of the frequency halving system of Figure 1 is composed of,two sinusoidal components of different frequencies and of substantially equal amplitudes, it is onlyfor certain particular relative frequency values of said components that voltages components having frequencies respectively equal to onehalf the frequencies of the two input voltage components are developed at the terminals of one of the two transformers 63, 64. But I have found that, irrespective of the relative frequency values of the two input voltage components of the system, a voltage of frequency equal to one-half the frequency of one of these input voltage components is developed across the secondary winding of the transformer 83, while a voltage of frequency equal to one-half the frequency of the other frequency component of said input voltage is developed across the secondary winding of the transformer 64. These two voltages thus complement each other, and in applying them to the common circuit 6l--63, a voltage may then be obtained, comprising components having frequencies respectively equal to onehalf the frequencies of the two components of the alternating voltage applied to the input terminals 45, 46, and having a wave shape approaching that of said input voltage, if the phase shifting device 69'|0 is properly adjusted.

Similarly, when the input voltage energizing the terminals 45, 45 comprises more than two different frequency components, and depending, to some extent, on the relative frequencies, phases and amplitudes of said components, the voltages developed, respectively, in the transformers 53, 84 are in a measure complementary, and the application of these two voltages to a common circuit 6l68 permits to obtain, more completely than through either one of these, a sub-multiple frequency reproduction of the alternating voltage applied to the input terminals 45, 4

While the system illustrated in Figure l is shown as utilizing two frequency halving devices, the same disposition of its various circuit elements may be used with two frequency dividers D, D and a frequency multiplier E of other frequency transformation ratios, providing that the input-output frequency ratio of each of the frequency dividers D, D is equal to the outputinput frequency ratio of the frequency multiplier E,'said ratios being measured when the devices are operated with applied alternating voltages of sinusoidal wave shape.

The system illustrated by the schematic diagram of Figure 2 is laid out according to the same general arrangement as the system of Figure 1, but with another disposition of the demodulating and output circuits. As in the system of Figure 1, a generator C, producing an alternating voltage of substantially sinusoidal wave shape, actuates a frequency multiplier E which supplies an alternating voltage of carrier frequency, multiple of the frequency of the generator C, to a modulator F. The modulating circuit terminals 45, 46 of this modulator F constitute the input terminals of the system and to these terminals is applied the alternating voltage, the sub-multiple frequency reproduction of which is to be developed across the output termihals 61, 68 of the system. The output terminals 41, 48 of the modulator F are connected, as in Figure 1, to the input terminals ll, I2 and 3|, 32 of two frequency dividers D, D respectively through a filter circuit H passing the low frequency side band output voltages of the modulator F and a filter circuit G passing the high frequency side band output voltages of said modulator. Theoutput terminals 3, I4 and 33, 34 of the frequency dividers are connected respectively between the gridand filament of coupling tubes H, 12, the plate circuits of-which are energized by a-battery 13. The plate circuits of these tubes are coupled, through transformers 14,15, to the circuit of an alternating current rectifier 16. This same rectifier'circuit is also coupled, through a transformer 11, to the plate circuit of a triode 18, energized by the battery 13, and the grid circuit of which is actuated by the voltage produced by the generator C. The circuit of the rectifier 16 also comprises a transformer I9 shunted i by a high frequency by-pass condenser tfll and the secondary winding terminals 61, 68 of said transformer constitute the output terminals of-thesystem. "Ihe'system of Figure 2 thus differs from-that of Figure 1 in that the outputvoltages ofthe twofrequency dividers D, D operate; together with a voltage derived from the generator C, inthe circuitof a common rectifier "|6,instejad of operating in the circuits of separate rectifiers 55,60 respectively.

Since the voltages developed acrossthe terminalsl3, l4 and 33, 34 by'thefrequency-dividers D, D' respective1y are of non-sinusoidal wave shape, filtercircuits I, J may be inserted between saidterminals and the circuit of the rectifier 16, so arranged asto pass the low frequency components of said voltages, and to attenuate-such harmonics thereof, particularly the third and higher, as may produce disturbing low frequency "components across the output terminals 61, 68

ofthesystem. 1

Furthermore, in order to permit an "adjustment of the phase relations between the output voltage components produced through the operation of one of the two frequency dividers and those producedby that of the other, a phase adjusting device 8|82, which may be similar-tothephase adjusting device 69-10 of Figure 1, may be connected between the output terminals 41, 48 of the modulator F and the input terminals ll, l2 or. 3|, 32 of either one of said dividers, or between the outputterminals I3, M, or 33, 34 of eitherLof said dividers and the circuitof the rectifier16. I

The system illustratedin Figure 3 follows the same general pattern as shown in Figure'2, but with another arrangement of the sources of the carrier voltage energizing the modulator F and the sub-multiple sinusoidal voltage actuating thedemodulating rectifier *circuit. Corresponding frequency divider similar to the frequency divid- D, D or vice-versa.

Q96, 91 is connected to the terminal l2. Figure l output terminals l3, M of the frequency cm D, D. connected to the output terminals 81, 88 of the generator K,while its output terminals 85, 86 are connected to the grid circuit of the coupling tube 18. This latter connection is preferably made through a resonator circuit formed, for instance-by a condenser 89 shunted by an inductance coil 90, tuned to the sub-multiple output frequency of the divider L, for the purpose "of supplying to the circuit of the rectifiers 16 an alternating voltage of substantiallysinusoidal wave shape. 3

- Or else, the frequency demultiplier L may be constituted by a multivibrator, synchronized by the generator K at a suitable multiple frequency, or by a synchronized submultiple frequency tuned oscillator, in which latter case the resonator circuit 89- 90 may, in 'some instances, be dispensed bination frequency voltages in their respective circuits, proportionalto,therproduct of the voltages applied to said circuits, modulating circuit arrangements and devices may be used instead of these rectifiers, through Which the sub-muL- tiple frequency sinusoidal voltage supplied by the generator 0 or demultiplier L is made to modulatethe output voltages of the frequency dividers Finally, ,whenthe alternating voltage applied to the input terminals 45,46 of the system comprises several components of different frequencies; the alternating voltages actuating the input terminals l2 and. 3|, 32 of the frequency dividers undergo wide variations of their maximum amplitudes. The reversible apparatus formed by thetubes 'l, 2 and 2|, 22 and their associated circuit elements should then preferably be adjusted to operatewith small reversing voltages,

Amplification of put terminals of the dividers D, D. e

Moreover, the difierentialrvoltages developed by the'tubes 9, l0 and 29, 30 of the frequency dividers may be amplified before being applied to the circuits of their corresponding triode pairs 2 and 3|, 32 respectively. One possible manner of achieving this is illustrated in Figure 4, which shows the circuits of the system B of the divider D-of Figure 1, to which an intermediate amplification-stage as just set forth has been added.. Thus, the resistances 6, I through which the filaments of" the tubes I. 2 re nne d t each other, instead of being connected in the plate'circuits of the rectifiertub'es 9,10, are in cludedrespectively in the plate circuits of two triodes 9|, 92 energized by a battery 93 and operating as a push-pull amplifier. The grid circuits of these two triodes 9|, 92 comprise, respectively, resistances 94, 95, which are connected in series with each other across resistances 96, 91 'ofthe plate circuits of the tubes 9, l0 respectively. As in the arrangement of Figure 1, the

filaments'0f these tube 9, H! are connected to '70- the terminal H of the frequency divider, while the common connection point of the resistances Asin divider are taken off the plates of the tubes 9, Ill.

The system A of the divider D of Figure '1 being Its input'terminals 83, 84 are then altered in a manner similar to thatJshown in Figure 4 for the system B, the grids'of the tubes 9, of' the system B are connected,as before, to suitable points of the plate circuits of the tubes 2, I of the system A through wires 98, 99 respectively, while the grids of the tubes 9, ID of the system A are connected to suitable points of the plate circuits of the tubes I, 2 of the system B, through wires I00, l0l respectively.

What I claim is:

1. In a frequency dividing system for electric alternating currents comprisin a modulated wave alternating carrier current generator'including a source of alternating carrier current and a-modulating circuit and two modulating voltage input terminals and two modulated voltage output terminals, the combination of two frequency divider having equal frequency transformation ratios and each provided with a pair of actuating terminal and a pair of output terminals, frequency selective means for coupling said actuating terminals to said modulated voltage output terminals in such a manner that one of said dividers shall be actuated by the upper side frequency components of said modulated voltage and the other of said dividers shall be actuated by the lower side frequency components of said modulated voltage, a source of alternating current having a substantially sinusoidal wave shape and a frequency which is a sub-multiple of the carrier frequency of said generator in the same ratio as the frequency transformation ratio of each of said dividers an output circuit, and alternating current demodulating means coupled to said source of sinusoidal current, to said output terminals of said dividers and to said output circuit.

2. In a frequency dividing system for electric alternating currents comprising a modulated wave alternating carrier current generator including a source of alternating carrier current and a modulating circuit and two modulating voltage input terminal and two modulated voltage output terminals, the combination of two frequency dividers having equal frequency transformation ratios each provided with a pair of actuating terminals and a pair of output terminals, frequency selective means for coupling said actuating terminals to said modulated voltage output terminals in such a manner that one of said dividers shall be actuated by the upper side frequency components of said modulated voltage and that the other of said dividers shall be actuated by the lower side frequency components of said modulated voltage, a source of alternating current having a substantially sinusoidal wave shape and a frequency which is a sub-multiple of the carrier frequency of said. generatorin the same ratio as the frequency transformation ratio of each of said dividers, two alternating. current rectifiers, means; for coupling one of said rectifiers to said source of sinusoidal current and to said output terminals of one of said dividers, means for coupling the other of said rectifier to said source of sinusoidal current and to said output, terminals of the other of said dividers, and means for coupling the circuits of said rectifiers to a, common output circuit.

3; In a frequency dividing system. for electric alternating currents comprising a modulated wave alternating carrier current generator including a source of alternating carrier current and modulating circuit and two modulating voltage, input terminals and two Tnodulated voltage output terminals, the combination of two frequency dividers having equal frequency transformation ratios and each provided with a pair, of actuating terminals and a pair of output terminals,.frequency selective means for coupling said actuating terminals to said modulated voltage output terminals in such a manner that one of said dividers shall be actuated by the upper side frequency components of said modulated voltage and that the other of said dividers shall be actuated by the lower side frequency components of said modulated voltage, a source of alternating current having a substantially sinusoidal wave shape and a frequency which is a sub-multiple of the carrier frequency of said generator in the same ratio as the frequency transformation ratio of each of said dividers, an alternating current rectifier, an output circuit, and means for, coupling said rectifier to said source of sinusoidal current and to said output terminals of said dividers and to said output circuit.

4. v A frequency dividing system for electric alternating currents according to claim 1, in which said demodulating means are coupled to said source of sub-multiple frequency current through an alternating current phase adjusting device.

5. A frequency dividing system for electric alternating currents according to claim 1,- in which said output terminals of one of said dividers are coupled to said demodulating means through an alternating current phase adjusting device.

6. A frequency dividing system for electric alternating currents according to claim 1, in

said means for coupling said common output circuit to the circuit of one of said rectifiers include an, alternating current phase adjusting device.

9. A frequency dividing system for electric alternating currents according to claim 1, in which said demodulating means are coupled to said output terminals of said dividers through frequency selective means passing the lower frequency components of the output voltages of said dividers and attenuating the higher frequency components of said output voltages of said dividers.

10; A frequency dividing system for electric alternating currents according to claim 1, in which said dividers comprise circuit systems including each a reversible apparatus, rectifying relays provided with a differential output circuit, amplifying means provided with a control circuit and an output circuit, means for coupling said a control circuit to said differential output) circuit,

and means for coupling said output circuit of said amplifying means to said reversible apparatus.

11. A frequency dividing system for electric alternating currents according to claim 1, charratio is equal to the output-input frequency ratios of the dividers, and the low frequency circuit being coupled to the source of sub-multiple frequency current and the high frequency circuit to the modulating circuit.

12. A frequency dividing system for electric alternating currents according to claim 1, characterized by the provision of a frequency demultiplier affording a high frequency circuit and a HENRI LAUER. 

